1. Technical Field
Example embodiments of the present invention relate to an apparatus, method, and system for transmitting and receiving high-speed data in point-to-point (P2P) fixed wireless communication, and more particularly, to an apparatus, method, and system for transmitting and receiving high-speed data in P2P fixed wireless communication that may wirelessly transmit high-speed data using digital modulation/demodulation in transmission of a single carrier (SC) scheme of P2P fixed communication using microwave and millimeter wave bands.
2. Related Art
In general, a millimeter wave band refers to a high frequency between 30 GHz and 300 GHz, and has characteristics of a short wavelength and strong straightness close to light. Accordingly, the millimeter wave band is suitable for gigabit per second (Gbps)-level ultra-high-speed broadband transmission, and for low-power short-distance communication in the range of around 1 km due to atmospheric oxygen attenuation.
A frequency of the millimeter wave band is used for communication within university campuses, communication between buildings within a company, island to land communication, high-speed wireless local area network (LAN) communication, and intelligent transport systems (ITS) road side communication by constructing a backbone network for use in P2P fixed wireless transmission, and will also be useful for constructing a wireless communication network to establish a connection between a mobile communication base station and a base station controller in a mountain region or the like in which it is difficult to install an optical cable.
The millimeter wave frequency is internationally used for limited purposes of a wireless personal area network (WPAN), radar, an image sensor, fixed P2P communication, and the like. Recently, technical development and standardization (Institute of Electrical and Electronics Engineers (IEEE) 802.15.3c) of WPAN technology for transmitting uncompressed high-definition (HD) level video using a wide frequency bandwidth in a band of 60 GHz are actively ongoing.
In the case of the millimeter wave, a band of 7 GHz at 60 GHz and a wide band of a total of 10 GHz at 70/80 GHz at which each band is 5 GHz are allocated as frequencies for fixed communication all over the world. A wide bandwidth is significantly advantageous for transmission of high-speed data at Gbps or higher. Thus, many studies are being conducted on wireless communication as means for replacing a wired network because an optical communication rate is rapidly increasing to several tens of Gbps or higher due to the explosive growth in Internet use.
Currently, studies of the millimeter wave band (30 to 300 GHz) are actively ongoing to meet overwhelming domestic and international demand for wideband and ultra-high speed for information communication. A band of 20 to 40 GHz, which is a boundary between a millimeter wave band and a microwave band, is currently being extended for fixed and mobile on the basis of advanced technologies in satellite communication and military communication, and its application examples are a local multipoint distribution system (LMDS) in the US, a microwave video distribution system (MVDS) in Europe, and a broadband wireless local loop (BWLL) in Korea. A frequency band, which is gradually receiving attention, is a band of 60 GHz.
A band of 60 GHz (about 55 to 65 GHz) is available in various application fields because broadband transmission is possible and absorption attenuation of radio waves by oxygen is large. Its representative application examples are a satellite cross link, a military application field, a vehicle anti-collision system, various commercial large-capacity wireless systems, and the like. Application examples of the commercial system are a large-capacity, short-distance communication system, a wireless LAN, and a wireless home link, and the like. In addition, studies of a mobile communication system in which optical band communication is possible in connection with optical communication are actively ongoing. At present, a 60 GHz application system is expected to appear from fourth-generation mobile communication.
FIG. 1 is a conceptual diagram of a general transmission/reception system for use in P2P fixed communication using an analog scheme.
In FIG. 1, a P2P fixed communication system for wirelessly transmitting Gbps-level data using an analog scheme, particularly, an amplitude shift keying (ASK) scheme, is shown.
In the existing method as shown in FIG. 1, an Ethernet signal input from an Internet network is converted into an electrical signal capable of being processed through an optical to electrical (O/E) converter, and the electrical signal is up-converted into a desired frequency band in the ASK scheme using a diode modulator. After a variable attenuator is used to adjust output power, final output power obtained using a high power amplifier is transmitted on a radio channel of a millimeter wave band using an antenna. A received signal input to a reception stage through an antenna is processed in a reverse process.
As described with reference to FIG. 1, a P2P fixed communication method using an analog signal has an advantage in that implementation is simple and easy. However, this method has a limitation in that it will continuously increase a transmission rate in the future because frequency use efficiency is bad. In addition, because the analog signal is not available for reception sensitivity improvement and a digital signal processing function for reducing an error, the performance improvement of the entire system is largely limited.